Hydraulic pump unit



J. DELANEY 3,006,281

HYDRAULIC PUMP UNIT 2 Sheets-Sheet 1 Oct. 31, 1961 Filed July 8, 1960 IHIII M 4 ww mi.

ATTORNEY J. J. DELANEY HYDRAULIC PUMP UNIT Oct. 31, 19,61

2 Sheets-Sheet 2 Filed July 8, 1960 Ja/m J. Delaney 6m 06% kcrromvey Unted States Patent 3,006,281 HYDRAULIC PUMP UNIT John Joseph Delaney, 419 Luzerne Ave., West Pittston, Pa.

Filed July 8, 1960, Ser. N0. 41,600 Claims. (Cl. 103-37) This invention relates to pumps, and more particularly to a unitary dual action, dual capacity and dual pressure hydraulic pump.

In certain pumping operations it is necessary to operate the pump through several cycles before the resistance of the load is actually encountered. For example, in jacking up an airplane for purposes of making repairs, the jacks are usually placed under the wings of the plane, and the jack ram must iirst be brought into contact with the wing before the plane can be lifted. In order to lift this load, it is necessary to use a high pressure, low capacity pump, and due to the small outward movement of the ram, several cycles of the pump are required before the jack is brought into contact with the wing.

Heretofore, several methods have been suggested to provide for initial rapid elevation of the jack with a high capacity low pressure pump, followed by slower elevation eiected with a high pressure low capacity pump when the resistance of the load is encountered. 'Some of these suggestions contemplate the use of two or more pumps, with either manual or automatic change from low to high pressure when desired; other methods involve the use of dual capacity pumps, which may be manually or automatically regulated to adapt -the pump to increased load requirements. Generally considered, the previously suggested pump devices have intrinsic disadvantages, including complexity of design, expense of manufacture, and limited type of operation. Certain of the devices heretofore proposed are of the open type, and accordingly, must be maintained in one position for operation; most of the prior pump systems do not embody a proportionate relationship between the power exerted and the effective power obtained, and additionally, these systems are of the single action type in one or both phases, and in some instances they are limited as to the type of actuating power required.

The present invention comprehends the provision of a highly eliicient, versatile and economic pump unit which obviates the above noted disadvantages of the prior pump systems. The novel pump unit of the present invention comprises a dual action, dual capacity, dual pressure device constructed and arranged so that when an additional load is imposed on the low pressure phase the pump automatically -adjusts to become a high pressure pump to rthus accommodate and/or elevate fthe additional load. The improved pump unit is of true dual action in that all cycles are pumping cycles on -both the high and the low pressure phases; it is a dual pressure unit in that it functions automatically as either a high pressure or a :low pressure pump, depending on Whether the load impressed on the system is above or below some predetermined pressure, and it is a dual capacity unit in that the volume of the fluid pumped is large during the low pressure phase and, conversely, is small during the high pressure phase.

An object of the invention is to provide a hydraulic pump embodying a unitary piston structure operable at diterential uid pressures.

Another object of the invention is to provide a hydraulic pump embodying a unitary, bifunctional piston structure operable at diierential iluid pressures and capacities.

Yet another object of the invention is to provide a unitary, dual action, dual capacity, and dual pressure hydraulic pump.

Still another object of the invention is to provide a unitary, dual action, dual capacity hydraulic pump embodying a low pressure pumping system and a high pressure pumping system, constructed and arranged whereby to operate as a low pressure pump at a predetermined low pressure and to automatically function as a high pressure pump when such predetermined pressure is exceeded.

A tur-ther object of the invention is to provide a pump, adapted for use with hydraulic jacks, having a unitary bifunctional piston structure directly operable at differential pressures as a low or high pressure pump.

A still further object of the invention is to provide a pump, 'adapted for use with hydraulic jacks, having a unitary bifunctional piston structure operable on each cycle under preselected low and high fluid pressures.

Yet a still further object of the invention is to provide a hydraulic pump embodying unitary, dual action, coaxial pistons which are automatically operable at preselected fluid pressures.

With these and other objects in view, which may be incident to my improvements, the invention consists in the parts and combinations to be hereinafter set forth and claimed, with the understanding that the several necessary elements, comprising my invention, may be varied in construction, proportions and arrangement, without departing from the spirit and scope of the appended claims.

In order to make my invention more clearly understood, I have shown in the accompanying drawings means for carrying the same into practical eiect, Without limiting the improvements in their useful applications to the particular constructions, which `for the purpose of explanation, have been made the subject of illustration.

In the drawings:

FIGURE 1 is a sectional View showing the pump assembly, valve mechanisms, and associated uid reservoir;

FIG. 2 is a top plan view of the pump unit shown in FIG. 1; and

FIG. 3 is a sectional view taken on line 3-3 of FIG. 1.

Referring to the drawings, and more particularly to FIG. l, the assembly comprises a pump body 1, formed with a chamber 2. of relatively large diameter and -a coaxial communicating chamber 3 of smaller diameter, adapted to receive -a unitary specially designed piston 4 reciprocable in the coaxial chambers. The unitary piston embodies a central or median low pressure piston section 5, an integral upper piston section 6 of a selected diameter Iless than that of the piston section 5, and an integral lower high pressure piston section 7 of a diameter less than that of piston 5, but `greater than that of the upper piston section 6.

The pump body is provided with a top closure or head 8, secured thereto by means of bolts 9 (FIG. 2), said closure having a central bore 10 to receive the upper portion of piston section 6 for reciprocating movement therein, the piston being sealed by means of suitable packing 11, and a gland nut 12. The closure is adapted to carry or mount an actuating mechanism for reciprocating the unitary piston structure, and in the form shown, this may comprise a lever arm 13 pivotally connected as to 14 to the upper end of the piston section 6, and pivotably connected at a selected point 15 near its Ifulcrum end to a pair of links 16 (FIG. 2), the latter being pivotally connected as at 17 to the closure.

The pump body is positioned within a cylindrical uid container or reservoir 18, secured to a supporting ring 19, as by welding, adapted to seat in an annular recess 20 formed in the closure, the ring being detachably secured thereto by means of bolts 21 (FIG. 2).

The unitary piston structure, associated cylinder chambers and the cylinder closure or head are so constructed and arranged as to insure a novel, dual action, dual capacity and dual pumping operation in which the piston structure in toto functions on each stroke or reciprocation as a pump which is operable at a low pressure and automatically at a preselected higher'pressure by control of uid ow in the pumping system achieved by a novel correlation of piston design, fluid ducts, and uid control valves embodied in the pump assembly.

i The low pressure piston 5, 'and the lower portion 6' of the -upper piston section 6, are adapted to reciprocate in chamber-2, and the high pressure piston 7 is adapted to-reciprocate in chambersZ and 3. VIn the preferred embodiment the volume of the portion of piston 7, operable in the chamber 2, is twice that of piston section 6. YFluid tight reciprocation of the pistons 5 and 7 1s insured by any suitable sealing means, such as sealing rings 22 and 23, respectively.

Reference being had to FIG. l, it will be noted that the low pressure piston is formed with ducts 24 and 25 having opposedspring biased by-pass valves 26 and 27, respectively, which valves Vare adapted to be adjusted to seat at a predetermined pressure, so that when the fluid resistance in the system exceeds the predetermined pressure they will open on alternating strokes. The high pressure piston 7 is formed with a central bore 28 cornmunicating at its upper end with a lateral duct 29 whlch opens into the chamber 2 below the low pressure piston 5. The bore 28 is provided with a spring biased check valve 30 adapted to be adjusted so as to remain open during the up and the down strokes of the low pressure phase, andduring the down stroke of the high pressure phase, but closes during the up stroke of the high pressure phase, in the manner to be more fully described hereinafter.

The pump body V1 is provided with a port 31 in open communication at one end with the reservoir 18, and at its opposite end with a vertical uid duct V32, the upper end of which communicates with the chamber 2 above the low pressure VVpiston 5, through an interposed spring biased valve V34 and duct 35, which valve, as will be seen, controls the intake of iiuid from the reservoir during the down stroke of piston 5 in the low pressure phase and closes oif chamber 2 during ythe high pressure phase. The lowerend of duct 32 communicates through its eX- tension 32 with a duct 36 opening into the bottom of chamber' 3 below the high pressure piston 7. A spring biased valve 37 is interposed between .duct 32"and duct 36, and as will Ybe explained, functions to control the intake of uid from the reservoir during the upstroke of bothV the high and low pressure phases of the pump operation, YA vertical duct 38, having a lateral extension 38', communicates with the bottom of chamber 2 below the low pressure piston 5 through a spring biased valve 39 to permit discharge of fluid from the chamber 2 during the down stroke of the low. pressureV phase, and during both strokes of the high pressure phase; this valve also prevents back flow from the system during the upstroke of the low pressure phase. The duct 38 communicates with the reservoir 18 through a duct 40 having an interposed spring biased relief valve -41 adapted to be set at any desired pressure.

The closure or head number 8 is provided with a lateral discharge passage 42 communicating with a duct 43 opening into the reservoir 18, and a duct 44 aligned and communicating with the vertical duct 38. The discharge end 45 of the passage 42 is adapted to be connected to a hydraulic lift mechanism, not shown, and the opposite end of the passage is provided with a release valve,-designated generally by numeral 46, which valve is adapted to be manually operated by means of a knurled knob 47, to open or close communication between the passage y42 and the duct 43. The discharge passage 42 communicates with chamber 2 above the low pressure piston 5 through a duct *48 and an interposed 4 spring biased valve l49 which functions to permit uid flow into the discharge passage I42 during the up stroke of the low pressure phase and during both strokes of the high pressure phase; the Valve 49 also prevents back ilow from the system during the down stroke of the low pressure phase.

In the operation of the improved pump, assuming that the release valve 46 is closed, and that the discharge end y45 of passage 42 is connected to a hydraulic lift mechanism, reciprocation of the unitary piston 4 by means of the actuating lever 13 serves to draw uid from the reservoir 1 8 and dischargeV it through passage v42 to the lift mechanism, in either a low or high pressure operation. In the low pressure operation, Awherein the fluid pressure in the system is below that at which'the bypassyalves 26 and 27 are seated, these valves remain closed. During rciprocation, as the unitary piston moves upwardly, fluid from chamber 2 is forced out through valve 49 into the discharge passage `42; during the up stroke of piston 5 the back pressure against valve 39` prevents fluid from escaping back into the system, and simultaneously, intake'of uid from the reservoir is effected through a circuit comprising port 31, duct 32, valve 37, duct 36, and the central bore 28 of the high pressure piston 7 ,Yinto the chamber 2 through the lateral crluct.2 9.V .Qontemporaneously, valve 34 is seated by the back pressure of the fluid in the upper part of chamber 2.

On the down stroke `of the unitary piston, the pressure of the fluid closes valve 37 and the fluid is forced through the circuit comprising duct 38', valve 39, and the aligned ducts 38 and 414, into the discharge passage 42. Contemporaneously, intake valve 34 is opened and fluid from the reservoir 18 is drawn into the chamber 2, above the piston 5 through the duct 3S. It Will thus be seen that when the pressure in Vthe system is low, and the valves 26 and. 27 are closed, the unitary piston functions as a dual actingV piston, with the valves 34 and 37 alternating as intake valves, and the valves 49 and 39 alternating as exhaust valves. It will also be observed that in the above described phase of its operation, the pump unit operates as a lowV pressure, high capacity pump.

As the reciprocation of the unitary piston assembly is continued, and Ya back load or pressure from the hydraulic lift builds up a pressure on the system which exceeds the preselected biasing pressure on valves 26 and 27, these valves will unseat on alternating strokes, thereby permitting free passage of uid through the low pressure piston 5. When this occurs the low pressure piston 5, in eiect, is deactivated, and thereafter it is only the pump unit constituted by the axially aligned chambers 2 and 3, and the piston extensions 6 and 7 'which are effective in forcing working fluid through the passage 42 to the hydraulic lift. In this high Pressure phase of its operation, the pump unit functions as a high pressure, low capacity,'double acting pump.

. In the high pressure operation, assuming that the unitary piston 4 is at the end ofl its down stroke, it will be seen that on upward movement of the unitary piston Ythe upperV extension y6' will progressivelyv move out of the piston chamber 2 and into the head V8, and will be progressively Vreplaced in the chamber by the lower piston extension 7. Duringt-his stroke the valve 26 is open, Yand hence the pressureon eachrside of piston section 5 is-the same; valves 301and 34 are closed due to the back pressure of fluid thereon, and valve 37 is opened as fluid is drawn from the reservoir 18 through ducts `32 and 36 into the lower chamber 3 below the bottom of piston extension 7. During such up-stroke, thepressure of uid in chamber'Z unseats both valves 39 and 49, and the fluid flows. through Vduct 48 and'duct 38, respectively, into the discharge passage 42.

It will be noted that in this high pressure phaseV of the pump operation, the Vworking volume of the piston chamber 2 isreduced by'the volumes of the piston extensions 6 and 7, operating therein. Since-the volume of piston section 7 operable in chamber 2 is twice that of piston section 6', a volume of fluid equal to the difference between the volumes of these sections is forced into passage 42, and a volume `(twice that discharged) equal to the stroke-volume displacement of the piston section 7 is drawn into the pumping system.

On the down-stroke of the high pressure phase, the valves 27 and 30 are forced open by fluid pressure, and fluid in the lower chamber 3 ows upwardly through the bore 28, and duct 29 into the chamber 2. As the piston extension 7 recedes into its chamber 3, the descending upper extension 6 displaces a quantity of fluid equivalent to its volume through the valve 49 and duct 48, and simultaneously through valve 39 and duct 38, into the discharge passage 42. During the down stroke valves 34 and 37 remain closed, thus preventing back ow into the reservoir.

The maximum fluid working pressure of the pump unit may be preselected, and is controlled by the strength of the spring biasing the relief valve 41. As previously noted, the ltiuid pressure in the system may be released at any time, as after a particular lifting operation, by opening the manually operated valve 46 and bleeding uid from the passage 42, through duct 43 into the reservoir.

While the improved pump unit of the present invention has been described in 'connection with the actuation of hydraulic jacks, it is to be understood that the description of this use of the device is for purposes of illustration only, and that its useful application is not conned to the operation of hydraulic jacks or similar hydraulic lift mechanisms, since the improved pump is adapted for use with a variety of fluid pressure actuated devices of the character wherein a pushing or pulling force is to be exerted against a load or other resistance.

It will be appreciated that the improved pump can be actuated manually or mechanically by means ofa suitable motor, and that the pressures obtainable depend solely upon the power available and pressure necessary for this power. For example, it is possible to have a low pressure of 2O p.s.i. and a high pressure of 5,000 p si., both of which are automatically obtainable from a hand operated unit or from a combination of units. The pump is strong and sturdy in construction, economical to manufacture, easy to maintain, and it can be installed and operated at any angle with respect to the horizontal.

It is to be further understood, that while the novel pump unit has been described as having a piston structure of unitary construction adapted for reciprocation in coaxially arranged piston chambers, the present invention comprehends the provision of piston arrangements comprised of separate sections constructed and arranged fbor reciprocation in aligned or non-aligned piston chamers.

What is claimed is:

i 1. In a uid pump adapted to automatically change its displacement with changes in discharge pressure comprising, in combination, a iiuid supply reservoir, a pump body formed with a piston chamber of selected diameter and a coaxial chamber of less diameter, a unitary multiple function piston comprising an enlarged median section reciprocable in the piston chamber and provided with upper and lower integral coaxial plunger extensions of less diameter, the upper extension being reciprocable wholly within the piston chamber and the lower extension being reciprocable in the said piston chamber and within the lower coaxial chamber; valve means embodied in the median piston section, adapted to be closed at 10W operating pump pressure and to be opened at a predetermined higher operating pressure; valve controlled tluid inlet means connected with the reservoir and communicating with the upper end of the piston chamber and with the lower end of the coaxial chamber of less diameter; a rst valve-controlled discharge means connected with the upper end of the piston chamber and a second valve-controlled discharge means connected with the lower end of the piston chamber, and a valvecontrolled axial duct within the body of the lower coaXial plunger extension communicating at one end with the lower end of the piston chamber and at the other end with the lower end of the chamber extension of less diameter.

2. A pump according to claim l in which the valve means embodied in the median piston section comprises a pair of oppositely disposed spring-seated valves, each of said valves being adapted, on alternate strokes of the piston during high pressure operation, to establish direct communication between the upper and lower portions of the piston chamber.

3. A pump according to claim 1 in which, during low pressure operation, uid is discharged from the pump through the iirst said discharge line on the piston upstroke and through said second discharge line on the downstroke.

4. A pump according to claim 1 in which, during the high pressure operation, iluid is discharged from the pump chamber simultaneously through the said rst and second valve-controlled discharge lines.

5. A pump according to claim 3 in which, during low pressure operation, fluid is introduced into the upper portion of the piston chamber on the downstroke of the piston, through the axial duct of the lower coaxial plunger and into the lower portion of the piston chamber during piston upstroke.

6. A pump according to claim 1 in which, during the high pressure operation, fluid is discharged from the pump on both the upstroke and downstroke of the piston, and fluid is introduced from the reservoir through the axial duct of the lower coaxial plunger into the piston chamber on the upstroke only of the piston.

7. A pump according to claiml in which, during the high pressure operation, uid is discharged from the pump on both the up and down strokes of the piston and uid is introduced from the reservoir into the lower portion of the coaxial chamber extension.

8. A pump according to claim 7 in which the Volume of fluid introduced into the coaxial chamber extension is twice that discharged on the upstroke of the piston.

9. A dual action, dual capacity and dual pressure hydraulic pump of the character described, comprising a uid supply reservoir, a pump body for receiving fluid from the reservoir, said pump body being formed with a low pressure piston chamber of relatively large diameter and a coaxial chamber of less diameter; a unitary multiple function piston reciprocable in the chambers, said unitary multiple function piston embodying a central piston section operable in the low pressure piston chamber, an upper plunger extension operable in the low pressure chamber, and a lower plunger extension operable in the coaxial chamber and in the low pressure chamber, valve means embodied in the central piston section, adapted to be closed -at low operating pun-1p pressure and to be opened at a predetermined higher operating pressure; valve-controlled fluid inlet means connected with the tiuid reservoir and communicating with the upper end of the low pressure piston chamber and with the lower end of the coaxial chamber, Valve-controlled discharge means connected with the upper and lower ends of the low pressure piston chamber, and a valve-controlled duct within the body of the lower plunger extension communicating at one end with the lower end of the low pressure piston chamber and at the other end with the lower end of the coaxial chamber, whereby on each stroke of the unitary piston the pump operates as a low pressure pump at a predetermined low pressure, and automatically functions as a high pressure pump when the predetermined pressure is exceeded.

10. A dual action, dual capacity, and dual pressure pump according to claim 9, wherein the lower plunger 7 extension of the unitary multiple piston is of a selected diameter less than the diameter of the central piston section but greater than the diameter of the upper plunger extension operable in the low pressure chamber.

1l. A dual action, dual capacity, and dual pressure pump according to claim 10, in which, during the high pressure phase of operation, the volume of md introduced into the coaxial piston chamber on the upstroke of the unitary piston is twice that discharged Yfrom the low pressure chamber.

12. A dual action, dual capacity, and dual pressure pump according to claim 9, in which, during the low pressure phase of operation, uid from the reservoir is introduced into and discharged from the 10W pressure piston chamber on both the upstroke and the downstroke of the unitary piston, and during the high pressure phase of operation, fluid from the reservoir is introduced into the coaxial piston chamber during the upstroke only of the unitary piston.

13. A dual action, dual capacity, and dual pressure hydraulic pump of the character described, comprising a dluid supply reservoir, ya pump body for receiving uid from the reservoir, said body ibeing rformed with a low pressure piston chamber of relatively large diameter, and a communicating chamber of less diameter; a multiple function piston reciprocable in the chambers, said multiple function piston embodying a central piston section and an upper plunger extension operable in the low pressure chamber, and a lower plunger extension operable in the communicating chamber and in the low pressure cham.- ber, valve means embodied in the central piston section, adapted to be closed at low operating pump pressure and to be opened `at a predetermined higher operating pressure; valve-controlled fluid inlet means connected with the uid reservoir and communicating with the upper end of the low pressure piston chamber and with the lower end of the communicating chamber, valve-.controlled discharge means connected with the upper and lower ends of the low pressure piston chamber, and a valve-controlled 8 duct within the body of the lower plunger eXtensQn comf municating at one end with the low pressure piston chamber and at the other end with the communicating chamber, whereby on each stroke of the unitary piston the pump operates as a low pressure pump at a predetermined Y low pressure, and automatically functions as a high pres-Y sure pump when the predetermined pressure is exceeded.

14. A dual action, dual capacity, and dual pressure pump according to claim 13, wherein Athe plunger extension of the lmultiple piston operable in the communicating chamber and'in the low pressure chamber is of selected diameter less than the diameter of the plunger extension operable in the low pressure chamber but greater than the Vdiameter of the central piston section operable in the low pressure chamber,

15. A dual action, dual capacity, and dual pressure pump according to claim 13, in which, during the high pressure phase of operation, the volume of uid introduced into the low pressure piston chamber ou the upstroke of the multiple [function piston is'twice that discharged from the low pressure chamber.

References Cited in the rile of this patent UNITED STATES PATENTS 833,457 Hammond Oct.l6, 1906 918,167 Kohl et al. Apr. 13, 1909 1,046,073 Joyce Dec. 3, 1912 2,044,857 Pfauser f June 2,3, 1936 V2,922,373 P-ahl Jan. 26, 1960 vFOREIGN PATENTS 670,037 Germany Ian. 10, 1939 1,075,780 France Apr. 14, 1954 OTHER REFERENCES f German application (Kl. SC-lO/Ol), 1,007,215, May 9, 1957. 

